Elucidation of mechanisms of hormonal regulation of gene expression is an important and rapidly growing area of research. A number of protein factors that directly affect the initiation of specific gene transcription in specific tissues have been isolated. Examples include Pit-1 and TTF-1, which participate in the regulation of gene expression in the pituitary and thyroid, respectively. Progress in elucidating the precise roles played by these (and other) transcriptional factors is hampered by the lack of specific immunological reagents which recognize these molecules. It is the overall goal of this project to generate monoclonal antibodies against various DNA-binding transcriptional factors involved in hormonal regulation of gene expression. In Phase I, we plan to demonstrate the feasibility of our approach by developing antibodies against Pit-1 and TTF-1. Two strategies will be undertaken, utilizing a synthetic peptide approach to generate antibodies against specific epitopes of particular interest, as well as an approach utilizing tagged sequences produced in recombinant expression systems. The utility of the antibodies will be ascertained in both laboratory and clinical settings. Availability of such antibodies will have significant impact in furthering our understanding of the roles these molecules play in the control of differentiation and gene expression and have a number of potential clinical applications as well.